What a poor design.
You’ve replaced roughly every how many years?
Daft question: There’s no prevention solution then?
Replaced roof Seal : 2018 van
the dates below are when the work was carried out by the Dealer, not necessarily when the failure was reported.
# 1 (factory fitted seal)
noted as failed Aug19 - rust evident within the seal recess on (first clean / inspection of roof edge & seal) = failure on the rear corner replaced sept 19 - i.e seal #2 fitted:
#2 dealer fitted: noted as failed Aug 21 rust evident within the seal recess recess on front edge where roof profile blends from lower to upper level. Seal # fitted October 21
#3 Dealer fitted: Noted as failed Nov 21 - seal rust evident leaching from a small hole in the manufactured joint, front O/s corner. Reported several weeks after fitting of previous failed seal In Oct 21
#4 due to be fitted imminently I incidentally the photo above is of the font of the roof with the side tape (factory fitted) in the lower left of the photo. Dealers are instructed to clean the roof edge fully before fit replacement seals !
All failures have been at different points on the seal, the last I belive is purely a manufacturing fault that was not picked up during fitting, but the amount of rust observed leaching is more considerable than the previous two failures.
i will post this detail and some photos in another thread specifically related To this issue to assist other when carrying out specific search(s).
The roof is aluminium the top part og the van it bolts to is aluminium so no point the corrosion is caused by the steel strip in the rubber seal rusting and reacting with the aluminium roof Only way is to remove roof seal altogether.
vwcaliforniaclub.com
edit: importantly two have failed on the front of the roof where VW have omitted to fit the remedial “ tape” in an attempt to prevent this issue !
Clear there is still a major issue with this part and VW have failed to resolve the known issue since production of the T5, it is now being reported on T6.1 models.